Numerical Analysis On The Deformation Property Of Impervious Barriers Of Fiber Reinforced Clay Under Nonuniform Settlement

The nonuniform settlement of ground and waste mass of landfill may cause bottom liners and final covers crack. The impermeable property of liners and final covers decreased significantly. To some extent, fiber reinforced clay may improve this situation. This paper based on the existing test results of fiber reinforced laterite clay(FRLC), analyzing and generalizing that the hyperbola-straight line can describe stress-strain relationship of FRLC. On this basis, the three-dimensional model was developed to simulate triaxial test and centrifugal modeling test by numerical analysis. Numerical analysis for deformation characteristic of liners and final covers of hypothetical landfill was also performed under the nonuniform settlement. The main conclusion obtained from this paper was as follows:(1) The shear strength and absorbed strain energy of laterite clay(LC) may increase obviously after it reinforced with polypropylene fibers, increase with the increasing fiber contents and lengths. The stress-strain relationship of FRLC had hyperbola-straight line characteristic. The parameters of stress-strain curves were obtained by linear and nonlinear fitting method with test results. The piecewise points of axial strain ranged from5%to8%.(2) Based on ABAQUS, user’s subroutine of stress-strain relationship of FRLC was developed. The same three-dimensional model as the sample of triaxial test was developed, the triaxial test of FRLC was simulated through the numerical analysis method considering fiber lengths and contents and confining pressure. The numerical analysis was performed on the centrifugal modeling test of final covers of fiber reinforced soil in the reference by developing three-dimensional calculation model. There was a good agreement between the results of numerical calculation and test.(3) Due to a certain hypothetical FRLC liners and final covers in landfill on the onset of nonuniform settlement of ground and waste mass, the distribution of tensile strain and position of cracks were observed by numerical analysis. The results demonstrated that cracks can be restrained effectively when LC reinforced with fibers on the onset of nonuniform settlement. With an increase in fiber lengths and contents, an increasing trend of maximum settlement and critical tensile strain when cracks occured was observed. The anti-cracking property of LC was improved significantly with longer lengths and higher contents of fibers.